Effect of gamma irradiation on the structure of fucoidan

The change of molecular structure of fucoidan by gamma irradiation was analyzed by spectral and chemical methods. Fucoidan samples with different molecular weights of 85, 30, 15, and 7 kDa were prepared by radiation degradation of 217 kDa fucoidan. In the molecular weight analysis, the polydispersity decreased by gamma radiation because of further degradation of higher weight molecules. Ultraviolet absorption and Fourier-transform infrared spectroscopy analyses were carried out to define the changes of the functional groups in fucoidan by gamma irradiation. Carboxyl groups and carbon double bonds increased by gamma irradiation; however, sulfate content remained unchanged. The granular fissures were observed from scanning electron microscopy in gamma-irradiated fucoidan.